In a conventional refrigerant compressor of this type, a compression mechanism 105 and a motor 106 to drive the compression mechanism 105 are fixed inside a sealed housing 104 which comprises an upper end plate 101, a body section 102, and a lower end plate 103 as shown in FIG. 20. The source of power to the motor 106 is supplied from an external power supply (not shown) through a hermetic terminal 110 having an electrically conducting pin 109 insulated with a glass seal 108 on a cup-shaped metal member 107 which is hermetically sealed on the sealed housing 104.
A refrigerant is sucked through a suction pipe 111 leading to a refrigeration circuit (not shown) into the compression mechanism 105, compressed, and discharged under a high pressure into the sealed housing 104, and returned to the refrigeration circuit (not shown) through a discharge pipe 112. Therefore, the inside of the sealed housing 104 of this type of compressor is filled with a high-pressure refrigerant.
Although HCFC22 has heretofore been employed as a refrigerant for this type of compressor, a decision has been reached to completely abolish it in the future because of a possibility of depleting the ozone layer by its emission into the air. Among several alternative HFC-based refrigerants to replace HCFC22, R407C, which is a mixture of HFC125, HFC32, and HFC134a, and R410A, which is a mixture of HFC125 and HFC32, are considered to be promising candidates. While the discharge pressure of R407C is approximately equal to that of R22, the discharge pressure of R410A is approximately 1.7 times that of R22.
When using an alternative refrigerant having such a high discharge pressure in a high-pressure type sealed compressor in which the discharge pressure is applied to the sealed housing itself, the pressure-resistance strength of the sealed housing needs to be increased. However, in the above-mentioned prior art structure, as the internal pressure of the sealed housing 104 increases, the upper and lower end plates 101 and 103 swell outward gradually assuming a sphere-like shape. As the hermetic terminal 110 is fixed by welding to a flat section of the upper end plate 101, the deformation causes a stress on the cup-shaped metal member 107 of the hermetic terminal 110, thus deforming it and breaking the glass seal 108, thereby causing leakage of the high-temperature high-pressure refrigerant to the outside. In the prior art construction, as this is the section of which the pressure-resistance strength is the weakest, it is necessary to increase the pressure-resistance strength of this section in order to increase the pressure-resistance strength of the entire sealed housing.
Also, the joints between the sealed housing 104 and the connecting pipes for the refrigerant, namely, the suction pipe 111 and the discharge pipe 112, are parts with the weakest pressure-resistance strength after the hermetic terminal 110 because a tensile stress is exerted thereon due to the high pressure inside the sealed housing 104.